Sheared pipe cutter

ABSTRACT

A device for cutting through the exposed portion of drill pipe supported in an underwater blowout preventor which pipe has been sheared to provide for a quick abandonment of the drilling, said device including a mandrel with cutters pivotally mounted in windows, a pressure responsive piston engaging the cutter so that the cutters are moved to cutting position by movement of the piston, a bypass around the piston when it reaches the position at which cutting is completed, to provide a pressure signal therefor, a rotatable nose portion on said mandrel with suitable bearings allowing the mandrel to rotate with the nose portion engaging the blowout preventor which supports the pipe, means for guiding the elongate portion of the pipe into the mandrel above the cutters and a lower position piston lock to retain the piston at its lowest position with the cutters in supporting relation to the cut portion of the pipe to allow such portion to be removed from the remainder of the drill pipe. This abstract is neither intended to define the invention of the application which, of course, is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.

ate [1 1 1451 Nov. 19,1974

[ SHEARED PIPE CUTTER [75] Inventor: John E. Clark, Jr., Houma, La.

[73] Assignee: A-Z International Tool Company,

Houston, Tex.

[22] Filed: Nov. 2, 1973 [21] Appl. No.: 412,114

52 us. Cl. 166/55.6 [51] Int. Cl; E21b 29/00 [58] Field of Search 166/55, 55.6, 55.8, 298

[56] References Cited UNlTED STATES PATENTS 2,229,331 1/1941 Lowrey l66/55.6 2,481,831 9/1949 Erwin 1 166/55.6 3,080,241 3/1963 Campbell 166/55.6 3,174,548 3/1965 Webb l66/55.6

[ 5 7 ABSTRACT A device for cutting through the exposed portion of drill pipe supported in an underwater blowout preventor which pipe has been sheared to provide for a quick abandonment of the drilling, said device including a mandrel with cutters pivotally mounted in windows, a pressure responsive piston engaging the cutter so that the cutters are moved to cutting position by movement of the piston, a bypass around the piston when it reaches the position at which cutting is completed, to provide a pressure signal therefor, a rotatable nose portion on said mandrel with suitable bearings allowing the mandrel to rotate with the nose portion engaging the blowout preventor which supports the pipe, means for guiding the elongate portion of the pipe into the mandrel above the cutters and a lower position piston lock to retain the piston at its lowest position with the cutters in supporting relation to the cut portion of the pipe to allow such portion to be removed from the remainder of the drill pipe. This abstract is neither intended to define the invention of the application which, of course, is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.

9 Claims, 5 Drawing Figures PATENT 33v 1 91974 SHEET 2 BF 2 SHEARED PIPE CUTTER BACKGROUND OF THE INVENTION In offshore drilling because of storms and possible blowouts it has been the practice to set the blowout preventors on a section of the drill string and, with a special shear to sever the drill string near the blowout preventors. Thus with a storm approaching in an offshore location the major portion of the drill string can be left in the well bore, the drill string severed and while the upper portion is being recovered the drilling vessel can be moved to safety.

When it is desired to re-enter the well bore to resume drilling, difficulty is encountered with engaging the upper exposed portion of the drill string since it is partially flattened by the shearing.

SUMMARY The present invention provides an improved underwater pipe cutting device which will cut a sheared pipe stub above the blowout preventors in which it is supported but below the oval or flattened portion thereof to present a circular pipe stub above the blowout preventors which can easily be retrievedby conventional methods and equipment.

An object of the present invention is to provide a device for cutting the pipe stub above the blowout preventor in offshore drilling which assures that the flattened portion of the pipe stub is removed.

Another object is to provide an improved pipe cutting device which can cut a pipe stub at an underwater location a preselected distance below its flattened sheared end to provide a stub of circular section for recovery with normal tools.

A further object is to provide an improved underwater pipe cutting device which cuts the flattened sheared end of a pipe stub and captures the cut portion for removal with the device.

BRIEFDESCRIPTION OF THE DRAWINGS These and other objects and advantages of the present invention are hereinafter set forth with reference to the description of the preferred embodiment illustrated in the drawings wherein:

FIG. 1 is an elevation view of the preferred form of cutting device of the present invention shown in position surrounding a drill pipe stub projecting from a blowout preventor.

FIG. 2 is a partial longitudinal sectional view of th cutting device illustrating its position as it completes cutting.

FIG. 3 is another partial longitudinal sectional view of the cutting device illustrating its position for lifting the severed portion of the pipe.

FIG. 4 is a transverse sectional view taken along line 44 in FIG. 1 and illustrating the position to which the device is guided in relation to the pipe stub tqbe cut.

FIG. 5 is an elevation view of one of the guiding and centralizing lugs.

DESCRIPTION OF THE PREFERRED EMBODIMENT The preferred form of cutting device of the present invention as shown in FIG. 1 includes the mandrel 10 which is provided with suitable means such as the threads 12 for supporting the device from a pipe string 14. The pipe string 14 has a central bore 16 through which suitable fluid is delivered for actuation of the euttingdevice as hereinafter described;

The cutting device is shown in the drawings in surrounding relationship to a pipe stub 18 which has been sheared and is supported by the blowout preventor 20. The mandrel 10 defines a bore 22approximately the same size as bore 16 in its upper1 end and the enlarged bore 24 which is sufficiently large to be lowered around the pipe stub 18;

The cutting device is adapted to cut off the top flattened portion ofipipe stub 18 by rotation imparted to the device by the pipe string 14. The lower end of mandrel 10 includes a means for engaging the blowout preventor 20 and allowing the remainder of the mandrel 10 to rotate with respect thereto. Such means includes the nose 26 and the bearingmeans including the radial bearings 28 and the axial bearings 30.

The mandrel l0 defines three windows 32 in which are positioned the cutters 34. Such cutters are each pi votally mounted by the pins 36. The pins 38 extending across the upper portion of windows 32 prevent outward pivoting of the cutters 34.

The height at which the cutters 3 4 sever the pipe stub 18 is preselected by including in-the mandrel 10 the sub 40. Thus, the length which sub 40 adds to the distance from the lower end of nose 26 to the cutting level of cutters 34 determines the level at which the pipe stub L8 is cut.

Since the upper end of pipe stub 18 is flattened or oval shaped by virtue of its having been sheared, a means is included with mandrel 10 for guiding the mandrel 10 over the pipe stub 18 to assure that its corners do not become engaged in the windows 32. Such guiding means includes the lugs 42 positioned one below one of the windows 32 and the other directly opposite therefrom. The lower ends of the lugs 42 have a wedge shape as best seen from FIG. 5 to engage the corners of the pipe stub 18 and guide the mandrel 10 on to stub 18 so that the corners of stub 18. are prevented from catching in the windows 32 Once the device has been set over the pipe stub 18, the lugs 42 act as centering stabilizers to assure that the device remains approxiri tely centered on the .pipe being cut.

With the cutters 34 being pivotally mounted in the windows 32 of mandrel 10 a pressure responsive means is provided to positively force the cutters 34 to pivot inwardly to cutting position. Such pressure responsive means includes. the sleeve 44 which is slidably mounted within the bore 24 of mandrel 1 0, the neck 46 of sleeve 44 which extends into bore 22 and the orifice ring 48 mounted in the bore 50 of neck 46. The seal ring 52 which is mounted in a groove around the exterior of neck 46 providesa sliding seal between the exterior of neck 46 and the interior walls definingbore 2 2. The restriction to flow through the device created by the orifree ring 48 creates a pressure drop across the sleeve 44 and it responds to pressure differentials created to function as adriving piston to. actuate the cutters 34. The driving connection with the. cutters 34 is provided by the upper edge of the windows 54 in sleeve en- In cutting operations of this type it is desirable to have some indication on the surface of the completion of the cut. In the device shown such indication is provided by the telltale piston 58 which is slidably mounted in the bore 60 of neck 46 immediately downstream of orifice ring 48. The piston 58 is tubular in shape and includes the upper, middle and lower seals 62, 64 and 66 respectively, which provide sliding seals against the surface defining bore 60. The orifice ring 68 is secured within the lower interior of piston 58 to provide a pressure drop for actuation of piston 58. The ports 70 are defined in piston 58 to provide a bypass communication between its interior and exterior at a position between the middle and lower seals (64 and 66). The exterior of piston 58 between upper and middle seals (62 and 64) includes the upper cylindrical surface 72 intermediate cylindrical surface 74 of smaller diameter than surface 72 and the lower cylindrical surface 76 which has a diameter smaller than surface 74. These surfaces coact with the balls 78 in the ports 80 in neck 44 and the counter bores 82 and 84 and the bore 22 of mandrel as hereinafter explained.

The indication of the completion of cutting is provided by the movement of telltale piston 68 downward in bore 60 when the cutters 34 have reached their position as shown in FIG. 2, disengaging seal 66 from bore 60 and providing the bypass around orifice ring 68 through port 70 and bore 60 into the interior of sleeve 44. Normally the sliding movement of telltale piston 58 is prevented by the locking engagement of balls 78 within the ports 80 and between surface 76 and bore 22. When the sleeve 44 has moved downward to the position at which cutters 34 have completed the cut through pipe 18, ports 80 have moved into registry with counter bore 82 to allow balls 78 to move outward to the position shown in FIG. 2 whereby telltale piston 58 slides downward in neck 46 with balls 78 engaging the shoulder between surfaces 74 and 72.

With the completion of cutting and the signal of the completion by the change in pressure of the fluid in the pipe string 14, the cut portion of the pipe stub 18 is to be removed. This is accomplished by continued movement of sleeve 48 downward in mandrel l0 responsive to the pressure differential created by the orifice ring 48. This continued movement of sleeve 44 moves the cutters 34 to their horizontal position as shown in FIG. 3. In this position the balls 78 have moved into the counter bore 84 allowing telltale piston 58 to move downward with balls 78 in upper surface 72. In this position the piston 58 locks the sleeve 44 in its lower position assuring cutters 34 remain in supporting position to the cut portion of pipe stub 18. Pipe string 14 is raised and the device with the cut pipe are recovered. Thereafter recovery of the drill string and other operations proceed in a normal manner.

From the foregoing it can be seen that the improved underwater pipe cutting device of the present invention cuts a flattened sheared pipe a preselected distance below the end while providing a signal at the surface of the completion of the cut and providing for the recovery of the cut portion of the pipe.

What is claimed is: V I H l. A pipe cutter for cutting sheared well drill pipe comprising a tubular mandrel having means at its upper end for connecting with a pipe string,

a plurality of cutters pivotally mounted in windows defined by said mandrel,

a piston slidably mounted within said mandrel and adapted to engage said cutters to cam said cutters to a cutting position,

said piston having means for restricting flow of fluids through said piston during cutting by said cutters and a bypass whereby movement of said piston to a completed cutting position opens said bypass around said flow restricting means to provide a change in pressure of the fluid in the mandrel above said piston signaling completion of said cut.

2. A pipe cutter according to claim 1 including a nose rotatably connected to the lower end of said mandrel for resting on a blowout preventor supporting the pipe to be cut.

3. A pipe cutter according to claim 2, including a sub connected between said mandrel and said nose,

said sub having a preselected length whereby the height of the cut above said nose is preset by the length of said sub.

4. A pipe cutter according to claim 1, including guide means within said mandrel to engage and orient said mandrel with respect to any appreciable flattening of the pipe to be cut.

5. A pipe cutter according to claim 4 wherein said guide means includes a pair of guide pads secured within the lower interior of said mandrel said pads being triangular with the apex pointed downward,

said pads are secured within said mandrel in opposed relation to each other and with the space between the upper ends being out of alignment with said cutter windows.

6. A pipe cutter according to claim 1, wherein said flow restricting means includes a telltale piston slidably mounted within said piston in said mandrel,

said telltale piston in a first position defining a restriction to flow through said mandrel, and in a second position defining said bypass around said flow rcstriction, and

means for retaining said telltale piston in said first position until said piston has moved to said completed cutting position.

7. A pipe cutter according to claim 6, wherein said telltale piston has a third position to which it moves when said cutters have been moved to a radial supporting position and in such third position said telltale piston locks said cutters and their piston in such position.

8. A pipe cutter according to claim 6 wherein said telltale piston is slidable through a portion of said cutter piston and said retaining means includes at least one ball,

at least one port defined in said cutter piston,

radially and axially spaced coacting surfaces on said mandrel bore and the exterior of said telltale piston,

said ball being adapted to be retained in said port and in engagement with the upper of said mandrel surfaces and the lower of said telltale piston surfaces,

movement of said cutter piston to completed cutting position moving said" ball to a mandrel surface below said upper mandrel surface to thereby allow said telltale piston to move to its second position.

9. A pipe cutter according to claim 8 wherein movement of said cutter piston to a position positioning said 

1. A pipe cutter for cutting sheared well drill pipe comprising a tubular mandrel having means at its upper end for connecting with a pipe string, a plurality of cutters pivotally mounted in windows defined by said mandrel, a piston slidably mounted within said mandrel and adapted to engage said cutters to cam said cutters to a cutting position, said piston having means for restricting flow of fluids through said piston during cutting by said cutters and a bypass whereby movement of said piston to a completed cutting position opens said bypass around said flow restricting means to provide a change in pressure of the fluid in the mandrel above said piston signaling completion of said cut.
 2. A pipe cutter according to claim 1 including a nose rotatably connected to the lower end of said mandrel for resting on a blowout preventor supporting the pipe to be cut.
 3. A pipe cutter according to claim 2, including a sub connected between said mandrel and said nose, said sub having a preselected length whereby the height of the cut above said nose is preset by the length of said sub.
 4. A pipe cutter according to claim 1, including guide means within said mandrel to engage and orient said mandrel with respect to any appreciable flattening of the pipe to be cut.
 5. A pipe cutter according to claim 4 wherein said guide means includes a pair of guide pads secured within the lower interior of said mandrel said pads being triangular with the apex pointed downward, said pads are secured within said mandrel in opposed relation to each other and with the space between the upper ends being out of alignment with said cutter windows.
 6. A pipe cutter according to claim 1, wherein said flow restricting means includes a telltale piston slidably mounted within said piston in said mandrel, said telltale piston in a first position defining a restriction to flow through said mandrel, and in a second position defining said bypass around said flow restriction, and means for retaining said telltale piston in said first position until said piston has moved to said completed cutting position.
 7. A pipe cutter according to claim 6, wherein said telltale piston has a third position to which it moves when said cutters have been moved to a radial supporting position and in such third position said telltale piston locks said cutters and their piston in such position.
 8. A pipe cutter according to claim 6 wherein said telltale piston is slidable through a portion of said cutter piston and said retaining means includes at least one ball, at least one port defined in said cutter piston, radially and axially spaced coacting surfaces on said mandrel bore and the exterior of said telltale piston, said ball being adapted to be retained in said port and in engagement with the upper of said mandrel surfaces and the lower of said telltale piston surfaces, movement of said cutter piston to completed cutting position moving said ball to a mandrel surface below said upper mandrel surface to thereby allow said telltale piston to move to its second position.
 9. A pipe cutter according to claim 8 wherein movement of said cutter piston to a position positioning said cutters in radial supporting position moves said ball into registry with a third lower mandrel surface whereby said telltale piston moves to its third position with its upper surface engaging said ball and locking said cutter piston and said cutters in their supporting position. 